from random import choice


class RandomWalk:
    """
    一个生成随机漫步的类
    """

    def __init__(self, num_points=500):
        """
        初始化随机漫步的属性
        """
        self.num_points = num_points

        # 所有的随机漫步都初始于(0,0)
        self.x_values = [0]
        self.y_values = [0]

    def fill_walk(self):
        """计算随机漫步包含的所有的点"""

        # 不断的进行漫步，直到列表达到指定的长度
        while len(self.x_values) < self.num_points:
            # 决定前进的方向和沿着此方向前进的距离
            x_direction = choice([1, -1])

            x_distance = choice([0, 1, 2, 3, 4])
            x_step = x_direction * x_distance

            y_direction = choice([1, -1])
            y_distance = choice([0, 1, 2, 3, 4])
            y_step = y_direction * y_distance

            # 拒绝原地踏步,止步不前
            if x_step == 0 and y_step == 0:
                continue
            # 计算下一个点的x和y值
            x = self.x_values[-1] + x_step
            y = self.y_values[-1] + y_step

            self.x_values.append(x)
            self.y_values.append(y)

